Biomedical subjects

Cheng-Chung Lee

Publications and source records attributed to Cheng-Chung Lee.

31 records · Page 2Linked to original sources

PubMed2005

Cloning, purification, crystallization and preliminary X-ray crystallographic analysis of XC847, a 3'-5' oligoribonuclease from Xanthomonas campestris.

Oligoribonucleases are essential components of RNA and DNA metabolism and close homologues of genes encoding them are found not only in prokaryotes but also in a wide range of eukaryotes, including yeast and humans. Inactivation of the oligoribonuclease gene (orn) can result in cellular lethality. Despite their important biological function, they have been studied little from a structural point of view. In this report, the cloning, expression, crystallization and preliminary X-ray analysis of XC847, a DEDDh-type 3'-5' oligoribonuclease from the plant pathogen Xanthomonas campestris pv. campestris, a Gram-negative bacterium causing major worldwide disease of cruciferous crops, is described. The XC847 crystals diffracted to a resolution of at least 2.1 A. They are tetragonal and belong to space group P4(3)2(1)2, with unit-cell parameters a = b = 67.5, c = 89.8 A. One molecule is present per asymmetric unit.

Amino Acid Motifs↗

PubMed2005

Coating uniformity improvement for a dense-wavelength-division-multiplexing filter by use of the etching effect.

The uniformity of optical narrow-bandpass filters for dense wavelength division multiplexing (DWDM) has been improved by control of the coating parameters of electron guns and the ion source. The optical film was deposited by the electron gun and was etched by the ion source during the ion-assisted deposition process. The uniformity of the coating of a 100 GHz DWDM filter is better than +/- 0.003% over a circular area of 50 mm in diameter when such an etching process is used.

Journal Article↗

PubMed2005

Preparation, crystallization and preliminary X-ray characterization of a conserved hypothetical protein XC1692 from Xanthomonas campestris.

Xanthomonas campestris pv. campestris strain 17 is a Gram-negative yellow-pigmented pathogenic bacterium that causes black rot, one of the major worldwide diseases of cruciferous crops. Its genome contains approximately 4500 genes, one third of which have no known structure and/or function yet are highly conserved among several different bacterial genuses. One of these gene products is XC1692 protein, containing 141 amino acids. It was overexpressed in Escherichia coli, purified and crystallized in a variety of forms using the hanging-drop vapour-diffusion method. The crystals diffract to at least 1.45 A resolution. They are hexagonal and belong to space group P6(3), with unit-cell parameters a = b = 56.9, c = 71.0 A. They contain one molecule per asymmetric unit.

Bacterial Proteins↗

PubMed2005

Preparation, crystallization and preliminary X-ray analysis of XC2382, an ApaG protein of unknown structure from Xanthomonas campestris.

Xanthomonas campestris pv. campestris is the causative agent of black rot, one of the major worldwide diseases of cruciferous crops. Its genome encodes approximately 4500 proteins, roughly one third of which have unknown function. XC2382 is one such protein, with a MW of 14.2 kDa. Based on a bioinformatics study, it was annotated as an ApaG gene product that serves multiple functions. The ApaG protein has been overexpressed in Escherichia coli, purified and crystallized using the hanging-drop vapour-diffusion method. The crystals diffracted to a resolution of at least 2.30 A. They are tetragonal and belong to space group P4(1/3), with unit-cell parameters a = b = 57.6, c = 122.9 A. There are two, three or four molecules in the asymmetric unit.

Bacterial Proteins↗

PubMed2005

A putative polyketide-synthesis protein XC5357 from Xanthomonas campestris: heterologous expression, crystallization and preliminary X-ray analysis.

Xanthomonas campestris pv. campestris (Xcc) is a Gram-negative yellow-pigmented bacterium and is the causative agent of black rot, one of the major worldwide diseases of cruciferous crops. It also synthesizes a variety of polyketide metabolites that lead to important antibiotics. XC5357 is a putative 12.2 kDa protein of unknown structure from Xcc that is likely to be essential for polyketide synthesis. It was overexpressed in Escherichia coli, purified and crystallized using the hanging-drop vapour-diffusion method. The crystals belong to the triclinic space group P1, with unit-cell parameters a = 43.7, b = 43.7, c = 46.5 A, alpha = 65.0, beta = 64.9, gamma = 73.4 degrees, and diffracted to a resolution of 1.85 A.

Bacterial Proteins↗

PubMed2005

Cloning, expression, crystallization and preliminary X-ray analysis of a putative multiple antibiotic resistance repressor protein (MarR) from Xanthomonas campestris.

The multiple antibiotic resistance operon (marRAB) is a member of the multidrug-resistance system. When induced, this operon enhances resistance of bacteria to a variety of medically important antibiotics, causing a serious global health problem. MarR is a marR-encoded protein that represses the transcription of the marRAB operon. Through binding with salicylate and certain antibiotics, however, MarR can derepress and activate the marRAB operon. In this report, the cloning, expression, crystallization and preliminary X-ray analysis of XC1739, a putative MarR repressor protein present in the Xanthomonas campestris pv. campestris, a Gram-negative bacterium causing major worldwide disease of cruciferous crops, are described. The XC1739 crystals diffracted to a resolution of at least 1.8 A. They are orthorhombic and belong to space group P2(1)2(1)2(1), with unit-cell parameters a = 39.5, b = 54.2 and c = 139.5 A, respectively. They contain two molecules in the asymmetric unit from calculation of the self-rotation function.

Bacterial Proteins↗

PubMed2005

Effect of thermal annealing on the optical properties and residual stress of TiO2 films produced by ion-assisted deposition.

The effects of thermal annealing of titanium oxide films deposited by ion-beam assistance at annealing temperatures from 100 degrees C to 300 degrees C on the residual stress and optical properties of the films was investigated. The refractive indices and extinction coefficients increased gradually as the temperature was increased from 100 degrees C to 200 degrees C and then declined gradually as the temperature was increased further from 200 degrees C to 300 degrees C. The film lost oxygen and slowly generated lower suboxides as the annealing temperature was reduced below 200 degrees C, as determined by x-ray photoelectron spectroscopy (XPS). As the annealing temperature increased above 200 degrees C, the lower suboxides began to capture oxygen and form stable oxides. XPS measurements were made to verify both the binding energy associated with the Ti 2p line and the variation of the O 1s line. A Twyman-Green interferometer was employed for phase-shift interferometry to study the residual stress. The residual stress declined as the temperature was reduced from 100 degrees C to 200 degrees C because the lower suboxides reduced the stress in the film. Above 200 degrees C, the film began to capture oxygen, so the residual stress rose. At 300 degrees C, the film was no longer amorphous as the anatase was observed by x-ray diffraction.

Journal Article↗

PubMed2004

Genetic and biochemical study in a patient with glutaric acidemia type I.

Glutaryl-CoA dehydrogenase (GCDH) deficiency causes glutaric academia type I (GA-I), an inborn error of metabolism that is characterized clinically by dystonia and dyskinesia and pathologically by neural degeneration of the caudate nucleus and putamen. We report a case of GA-I in a 4-year-old boy. Analysis of blood acylcarnitines by tandem mass spectrometry (MS/MS) revealed a high concentration of glutarylcarnitine in the blood (0.59 microM). Organic acid analysis of urine via gas chromatography mass spectrometry revealed glutaric acid and 3-hydroxyglutaric acids. In order to search for mutations, the GCDH gene of the patient and his parents were amplified by polymerase chain reaction and subjected to direct sequencing. Two mutations were detected in the patient's GCDH gene. One was located in exon 7 (T713C), which caused a codon 238 leucine to proline substitution; the other was located in intron 10 (IVS10-2 A-to-C), and caused a splicing variation in intron 10 and exon 11. Genetic amniocentesis was requested when the patient's mother became pregnant again, but the fetus did not carry any mutation. Tandem mass spectrometry was successfully used to make the diagnosis of GA-I in this case via identification of genetic mutation. If GA-I can be diagnosed in the early onset or presymptomatic stage, effective therapy would reduce sequelae.

Amino Acid Metabolism, Inborn Errors↗

PubMed2003

Purification, crystallization and preliminary X-ray analysis of immunogenic virus-like particles formed by infectious bursal disease virus (IBDV) structural protein VP2.

Infectious bursal disease virus (IBDV) causes a highly contagious disease in young chicks and leads to significant economic losses in the poultry industry. VP2 protein, which consists of 452 amino-acid residues, is the primary immunogen of IBDV and contains the epitopes responsible for eliciting neutralizing antibodies. When the chimeric VP2 protein (rVP2H) of a local IBDV strain P3009 was expressed alone using the baculovirus system, virus-like particles of approximately 23 nm in diameter formed spontaneously. Highly pure rVP2H particles, obtained using ammonium sulfate precipitation, immobilized metal-ion affinity chromatography and gel-filtration chromatography, were successfully crystallized using the vapour-diffusion method. These crystals, with a maximum dimension of 0.4 mm, diffracted X-rays to 4.5 A resolution, but data were only collected to 6 A. Preliminary analysis of the diffraction data showed that the rVP2H crystals belong to the cubic space group P2(1)3, with unit-cell parameter 323.1 A. The icosahedral symmetry of the particles is clearly seen in the self-rotation function maps, with dyads and triads coincident with the crystallographic axes. Each asymmetric unit contains 1/3 of the particle, or 20 rVP2H subunits, and there are four particles in a unit cell, probably in a tetrahedral arrangement.

Baculoviridae↗

PubMed2002

Differential wavelength-scanning heterodyne interferometer for measuring large step height.

An interferometer based on the differential heterodyne configuration and wavelength-scanning interferometry for measuring large step heights is presented. The proposed interferometer is less sensitive to environmental disturbances than other interferometers and can accurately measure interference phases. A tunable diode laser is utilized to illuminate the interferometer and thus solve the phase ambiguity problem. Counting the interference fringes as the wavelength is scanned through a known change in wavelength directly determines the step height. Three gauge blocks of different lengths, 5, 10, and 50 mm, are individually wrung on a steel plate to simulate large step heights. Comparing the results measured by the proposed interferometer with those by the gauge block interferometer reveals that the accuracy is approximately 100 nm.

Journal Article↗

PubMed2002

Internal stress and optical properties of Nb2O5 thin films deposited by ion-beam sputtering.

The influence on the internal stress and optical properties of Nb2O5 thin films with ion-beam energy was investigated. Nb2O5 thin films were deposited on unheated glass substrates by means of ion-beam sputtering with different ion-beam voltage, Vb. The refractive index, extinction coefficient, and surface roughness were found to depend on the ion-beam energy. The stresses in thin films were measured by the phase-shifting interferometry technique. The film stress was also found to be related to Vb, and a high compressive stress of -0.467 GPa was measured at Vb = 850 V. The Nb2O5-SiO2 multilayer coatings had smaller average compressive stress as compared with single-layer Nb2O5 film.

Journal Article↗

PubMed2002

Type identification of autosomal dominant polycystic kidney disease by analysis of fluorescent short tandem repeat markers.

Autosomal dominant polycystic kidney disease (ADPKD), is an inherited disorder with genetic heterogeneity. The presence of renal cysts is an important clinical marker for ADPKD diagnosis, but in the early stage, renal cysts do not emerge in individuals who carry the defective gene. Therefore, it is necessary to establish a genetic method of diagnosis. Two ADPKD-related genes have been isolated: PKD1, located on chromosome 16p13.3, and PKD2, located on 4q21-22. In this study, we used fluorescent short tandem repeat (STR) markers to perform linkage analysis in six unrelated ADPKD families. Six markers were included in the PKD1 and five in the PKD2 analysis. Among these six ADPKD families, four showed linkage to PKD1 and two showed linkage to PKD2. Ultrasonography or computerized tomography revealed that PKD1 patients developed cysts only in kidneys, but PKD2 patients developed cysts in kidneys, liver and pancreas. Our results indicate that fluorescent STR linkage analysis is well suited for type identification of ADPKD and presymptomatic diagnosis in ADPKD families.

Genetic Linkage↗

PubMedDate not supplied

Improvement of esophageal and gastric motility after 2-week treatment of oral erythromycin in patients with non-insulin-dependent diabetes mellitus.

Forty-five patients with non-insulin-dependent diabetes mellitus (NIDDM) were enrolled in the study. Before and after the 2-week treatment course of oral erythromycin, esophageal (the mean transit time, MTT) and gastric motility (the halftime of gastric emptying, GETt1/2) were evaluated by radionuclide labeled liquid and solid meals. Meanwhile, the fasting blood sugar (FBS) levels were monitored. After a 2-week erythromycin treatment, MTT shortened from 9.32+/-1.12 to 6.28+/-0.91 s and GETt1/2 shortened from 210.2+/-24.3 to 128.3+/-30.1 min. Meanwhile, FBS decreased from 198.2+/-30.1 to 121.5+/-21.3 mg/dl (P value <.05). We conclude that a 2-week treatment course of oral erythromycin can significantly improve esophageal and gastric motility which results in a better control of blood sugar in patients with NIDDM.

Administration, Oral↗